Building on top of
Legendary there’s
Streamist, which enables functional, promise-based interactions
with Readable streams, and
Aitch, a toolkit for constructing hypertext service clients.
Thenstream
can be used to construct a Readable stream from a thenable.

Other packages are
chai-sentinels, which helps passing sentinel values through your
code and asserting the results with Chai,
and sixtyfour,
a set of Base64 utilities.